Configuration method for a power supply controller and a controller employing same

ABSTRACT

The present application is directed at pin programming od controllers for power converters and provides for the programming of a plurality of different controller parameters using a single programming resistor. The value of the programming resistor is used as a pointer to select a table storing a plurality of different settings for the controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Patent Application filed under35 U.S.C. § 371 of International Patent Appln. No. PCT/EP2011/066365filed Sep. 20, 2011, which claims priority to British Patent Appln. No.1017395.3 filed Oct. 14, 2010, and U.S. Provisional Patent Appln. No.61/393,315 filed Oct. 14, 2010, the entire contents of all of which arehereby incorporated by reference as if fully set forth herein for allpurposes.

RELATED APPLICATIONS

The present application is related to and claims the benefit of priorityto each of U.S. Provisional Application No. 61/393,315 filed 14 Oct.2010 and GB Patent Application No. 1017395.3 filed 14 Oct. 2010, theentire contents of each of which are hereby incorporated by reference.

FIELD OF APPLICATION

The present application relates to controllers for power supplies, forexample controllers for switch mode power converters.

PRIOR ART

Power supplies, including for example power converters, are used toprovide power to a load. Power converters of which DC-DC converters arean example are employed to convert an input DC voltage to another DCvoltage. DC-DC converters may be classified generally as linear orswitching. A conventional arrangement for a switching DC-DC converter 1as shown in FIG. 1 uses a power stage 3 comprising one or more switchingdevices and one or more inductors or capacitors or both to convert aninput voltage (V_(in)) to an output voltage (V_(out)). A controller 5 isemployed to try and maintain the output voltage at a desired set point.Conventionally, pulse width modulation is employed to control theoperation of the switching devices within the power stage andaccordingly the controller provides a control signal to a PWM modulewhich operates the switching devices. A variety of different switchingcircuit topologies may be employed within the power stage which will befamiliar to those skilled in the art, including for example theconventional buck and boost topologies. In a linear switching supply,the gain of a transistor(s) or similar device is adjusted to achieve adesired output from an input voltage.

The output (V_(out)) from the DC-DC converter is typically provided to aload (not shown) which may be an electronic circuit comprising aplurality of components or just a single component, for example an LEDlight. Power controllers are used to control the operation of the powerconversion (switching) circuit to ensure a desired output (e.g. voltage)is provided to the load. Whilst the controllers may be implemented usinga discrete circuit, it is more common, for example in point of loadcontrollers which are designed to be used on-board close to the actualload being supplied, for the controller to be provided in an integratedcircuit.

To facilitate circuit designers and to ensure that one controller may beemployed in a variety of different configurations, at least some of theoperating parameters of controllers are generally configured to be setby a circuit designer.

Facilitating configurable operating parameters of controllers allows acircuit designer to select desirable behaviour in a particular powerconversion application. Operating parameters include, for example, butare not limited to,

-   switching frequency-   maximum duty cycle-   over-current protection (OCP) threshold-   over-temperature protection (OTP) threshold-   input voltage under-voltage lockout (UVLO) threshold-   device address for communication purposes, and-   loop control coefficients.

The setting of individual parameters may be performed by programming thecontroller. This programming may for example, be achieved through serialdata transmission in which the parameters are sent to the controller andstored in memory. This function may be performed initially during acustomisation stage performed at the time of circuit or controllermanufacture. This approach is typically not available to an end user butinstead is programmed in advance by the controller manufacturer.

An alternative and more common approach to configuring operatingparameters is pin-programming. In pin-programming, the setting of anoperating parameter is performed using a component connected to anassociated configuration inputs (pin on the integrated circuit) of theconverter. Using this approach, a circuit designer can set theparameters of a controller within a circuit by appropriate selection ofcomponents connected to the configuration inputs. The presentapplication is directed to pin-programming.

In pin-programming, a measurement is made of an external componentconnected to the pin. For convenience, this measurement is typically oneof resistance with the external component being a resistor. Although,other components and thus measurements may also be employed including,for example, capacitance are possible.

An example of a known controller configuration scenario using resistorprogramming for five different configurations is shown in FIG. 1. Theleft-hand side of the controller shows five configuration inputs(VSET—Output voltage set-point, ADDR—Communication address which mightbe a I2C or SMBus address the device will respond to when queried by acommunication master, FSW—Switching frequency, CLM—Output current limit,UVLO—Input Under-Voltage LockoutEach) with each input being anassociated pin on the controller.

Each configuration pin is connected to one end of an externalprogramming resistor (R_(VSET), R_(ADDR), R_(FSW), R_(CLM), R_(UVLO))with the opposite end of the resistor tied to a known voltage referencetypically ground. The value of the external resistor is used to set(program) the configuration value associated with the pin. In operation,current sources within the controller are configured to inject a knowncurrent into each of the configuration resistors. From this injectedcurrent, a determination of the resistance of the external programmingresistor is possible by measuring the voltage at the configurationinputs (pin). The voltage measurements are typically performed by one ormore Analog to Digital Converters within the controller. Once ameasurement has been obtained for each of the configuration resistors,the operating parameter assignments are made by the controller based onthe measurement of the individual resistors. In this particular example,only five operating parameters are assigned (output voltage set-point,device address, switching frequency, current limit threshold,under-voltage-lockout threshold). In practise, there may be many moreconfiguration pins.

Where no resistor is present, the controller typically defaults to aparticular value, generally the maximum or minimum of the availablerange.

In this exemplary configuration, other operating parameters remain attheir default values which will have been pre-defined by the controllermanufacturer. Once the operating parameters are set, typically duringstart-up, the controller enters its normal operating mode in which thecontroller operates to deliver power to a load. More particularly, thecontroller provides switching signals to one or more switches in a powerstage. The switches of the power stage in combination with energystorage devices such as inductors and capacitors operate to convert aninput voltage to an output voltage. The controller receives ameasurement of output voltage and operates to maintain this at a desiredlevel set by one of the configuration pins.

Techniques are known in which a single pin on a controller may be usedto set more than one operating parameter. Typically such techniques relyupon using two or more measurements at a pin. For example, in onearrangement, the polarity of the voltage at a pin is used as onemeasurement and the absolute value of voltage used as a secondmeasurement, with the polarity determining the value of one operatingparameter and the absolute voltage another operating parameter.Similarly, in place of using a single resistor to program, a capacitorresistor combination might be used. In this arrangement, a measurementof the resistance of the resistor and the capacitance of the capacitormay be employed as two separate measurements to set two respectiveoperating parameters. Similarly, it is known to sense for more than oneoperating condition, e.g. fault detection, at a single pin.

Whilst these techniques can reduce the pin count on the integratedcircuit of a controller, a typical controller may have between 50 to 100different operating parameters which may be altered to achieve a desiredoperating configuration or performance. Typically, a significant numberof these would be preset by the controller designer when designing thecontroller. However, circuit designers are desirable to having access tomore of these parameters to optimise the performance or configure thecontroller's operation as a component within their circuits.

Whilst providing greater access to parameters allows circuit designersgreater flexibility, there is a downside. The cost of convertersincrease with each configuration input added (due to increased siliconarea as I/O pads are added, increased bonding cost, increased cost ofsilicon package, etc). The cost for the circuit designer also increasesas one programming resistor is added to the build of materials (BOM) foreach configuration input. As components are added to the BOM, systemreliability is reduced (as expressed in Mean Time Between Failure(MTBF)).

SUMMARY

The present application provides for the setting of a plurality ofdifferent values using a single component. Thus reducing the number ofI\O pads and parts required.

In a first arrangement, a method of configuring a controller for a powersupply is provided. The controller is an integrated circuit having aplurality of pins, The controller has a plurality of settingsconfigurable by a user. The method comprises performing a measurement ata pin and using said measurement to determine two or more of thesettings. The using of said measurement may comprise the steps ofderiving a pointer from the measurement and using the pointer toretrieve a reference table having at least one setting. The method maycomprise the step of programming at least one setting in the referencetable, for example during the manufacture of the integrated circuit.

The reference table may be within a programmable memory. The referencetable may be programmable through a communications port, for example aserial port, on the controller.

In a second arrangement, a controller for a power converter is provided.In this second arrangement, the power converter is of the type havingone or more power switches operable in response to switching signalsfrom the controller. The controller is provided in an integrated circuitand comprises at least one programming pin to which an externalprogramming component may be connected. A measurement circuit performs ameasurement of the at least one external programming component. Thecontroller is configured to determine two or more of the settings forthe controller from said programming pin. The controller may comprise amemory for storing a plurality of configuration tables, with eachconfiguration table storing a plurality of different parameter settings.The measurement circuit suitably comprises an analog to digitalconverter. The controller may employ the measurement to derive a pointerand uses the pointer to retrieve a configuration table from a memory. Inturn this pointer may be obtained from a pointer reference table, whichmay be stored in memory, using the measurement or a derivation of themeasurement as an input. The memory may be programmable, optionallyduring manufacture of the integrated circuit.

Data for programming in the memory may be received through acommunications port on the controller. At least one of the settings maybe a set point for output voltage.

Thus, the present application provides a solution by which pinprogramming of one pin in a converter may be employed for the setting ofmore than one configuration setting.

The present application reduces to a minimum the required number ofconfiguration inputs, and external configuration components and/orallows for more comprehensive POLC configuration. This is achievedthrough the method of configuration tables, and mapping of configurationinputs/components in order to select one of these configuration tables.A configuration table is a list of assignments of values to POLCoperating parameters. A configuration table may be fixed orprogrammable, and may be of arbitrary length (i.e. a configuration tablemay contain an arbitrary number of assignments of values to operatingparameters).

DESCRIPTION OF DRAWINGS

The present application will now be described with reference to thefollowing drawings in which:

FIG. 1 is a simplified representation of a prior art power converterwith pin programming providing for the programming of 5 differentsettings in a controller using five separate resistors,

FIG. 2 is a representation of an exemplary implementation of the presentapplication allowing for the configuration of the same 5 differentsettings of FIG. 1 with a single resistor,

FIG. 3 is an exemplary flow chart of a method for use in the arrangementof FIG. 2;

FIG. 4 is a block diagram of an exemplary POL power converter for use inthe arrangement of FIG. 2;

FIG. 5 is illustrates an exemplary arrangement of tables which may beemployed in the arrangement of FIG. 2; and

FIG. 6 is illustrates a further exemplary arrangement of tables whichmay be employed in the arrangement of FIG. 2.

DETAILED DESCRIPTION

The present application will now be described with reference to anexemplary implementation of a controller, as shown in FIG. 2, providingfor the setting of the five parameters of FIG. 1 using just a singleprogramming resistor and programming pin.

As with the prior art, a measurement is made at a programming pin 16. Apin programming feature is provided to determine the value of theprogramming resistor. For example, a current source internal to thecontroller may be provided providing a current to the pin and in whichcase the measurement at the pin is suitably one of voltage, which inturn is a measure of the resistance of the configuration resistor. Thisresistance measurement is employed to retrieve a setting for each of thedifferent configuration parameters.

More specifically, once a measurement of voltage has been taken, thecontroller, using for example the method of FIG. 3, determines theconfiguration settings to use for the particular programming value ofresistor. Whilst in the exemplary circuit shown, five differentparameters are set by the one resistor, in practise it may be as low astwo or up to and including all of the available parameters in aparticular controller. Preferably three or more parameters are set bythe value of one resistor.

To account for variations in resistor resistance values from theirnominal values, a margin of error may be employed in determining whatthe programming value (resistor) connected to the pin is. This margin oferror may comprise dividing the voltages into ranges (bins) anddetermining the programming value from the range into which the measuredvoltage falls. Once a programming value has been determined 32 to bewithin a range (bin), a configuration table pointer for that range maybe derived 34. This derivation may be inherent. For example, a pointervalue of 1 may correspond to the first voltage range, with a pointervalue of 2 to the second range and so on. Alternatively, a look-up tableor other method may be employed to obtain the pointer from thedetermined range. The reason for this is simple and would be wellunderstood by those with even a basic knowledge of electronics.Specifically, that resistors are available in standard values but theseresistance values are the nominal ones and the actual value may vary ina range determined by the resistor tolerance. Thus in looking at ameasurement of resistance, the controller is seeking to determine notnecessarily the precise value of resistance attached but instead todistinguish between one standard resistance value and another. Thus ifthe controller was configured to be programmed by one of a 1 k, 2.2 k,3.3 k, 4.7 k or 5.6 k resistor, the number of different resistorbins\ranges would be five with each range corresponding to one of thestandard resistance values. Thus a pointer value of “1” might beassigned to any resistance between 0 and 1.6 k, with a pointer value of“2” being assigned to values between 1.6 k and 2.7 k and so on.

Alternatively stated, a continuous value range of R_(CONFIG) is suitablysegmented (sub-divided) into distinct resistance bins, with each binallocated to a particular pointer value. The number of distinctresistance bins, and thus pointer values, which can be reliably detectedand distinguished depends on limitations of the circuit blocks involved(ADC accuracy and resolution, bias current accuracy, resistor accuracyetc). However, if the number of R_(CONFIG) bins is not sufficientlyhigh, a second configuration input, with a second R_(CONFIG) may beemployed. It will be appreciated that this increases the possible numberof different bins values significantly since the inclusion of an extraprogramming pin squares the number of bin values compared to a singlepin with the inclusion of a third pin, the number of bin values isincreased by the power of three.

If the value of measured voltage falls outside all of the ranges, thecontroller may set 36 the pointer value to a default value. Similarly,if no pointer is allocated to a range a default pointer may be assigned.

The controller may then employ the pointer value to retrieve 38 aconfiguration table from memory. For each pointer there may be acorresponding configuration table. Each configuration table stores aseparate parameter value for each of the settings. Exemplary variablevalues for a configuration table are shown below corresponding to thosevariables determined by the five separate resistors shown in FIG. 1:

Vset Output voltage set-point Addr Communication address, for example anI2C or SMBus address, which the device will respond to. FSW Switchingfrequency CLM Output current limit UVLO Input Under-Voltage Lockout

It will be appreciated that rather than allowing a circuit designer tochose different parameter values, this method allows the circuitdesigner to chose different configurations of parameter values.

Other exemplary parameters that may be set within a configuration usingthis method would include but are not limited to one or more of thefollowing:

-   VOUT_MAX: Maximum output voltage set-point which can be commanded-   VOUT_MARGIN_HIGH: Output voltage set-point for margin high test-   VOUT_MARGIN_LOW: Output voltage set-point for margin low test-   VOUT_OVP: Output voltage Over-voltage protection trip-point-   VOUT_OFFSET: Output voltage offset correction parameter-   VOUT_ON_RISE_TIME: Output voltage rise time-   VOUT_ON_DELAY: Output voltage ramp delay following an ON command-   VOUT_OFF_DELAY: Output voltage ramp delay following an ON command-   VIN_UVLO_RESPONSE: Programmable response to UVLO condition    (immediate shutdown, delayed shutdown)-   VIN_OVLO_THRESOLD: Input voltage over-voltage protection threshold-   VIN_OVLO_RESPONSE: Programmable response to OVLO condition    (immediate shutdown, delayed shutdown)-   IOUT_OCP_RESPONSE: Programmable response to OCP condition (immediate    shutdown, delayed shutdown)-   IOUT_LCP_PROTECTION: Output current lethal protection (ultra-fast    but coarse threshold, amends OCP)-   IOUT_PHASE_DROP_ENABLE: Phase drop feature (on/off)-   IOUT_PHASE_DROP_THRESHOLD: Output current phase drop threshold-   OTP_THRESHOLD: Over-temperature protection threshold-   OTP: RESPONSE Programmable response to OTP condition (immediate    shutdown, delayed shutdown)-   OPERATION_RESPONSE: Programmable response to OPERATION command    (ignore, accept)-   CTRL_RESPONSE: Programmable response to CTRL pin (ignore, accept)-   CTRL_POLARITY: Programmable polarity of CTRL pin (active high,    active low)-   DUTY_CYCLE_MIN: Minimum duty cycle-   DUTY_CYCLE_MAX: Maximum duty cycle-   MOSFET_DRIVER_TYPE: Tristable, diode emulation, etc.-   MULTI_STRESS_SHARE: Multi-POL stress share feature (on/off)-   MULTI_SYNC: Multi-POL synchronisation feature (on/off), and-   MULTI_SYNC_PHASE_SHIFT: Multi-POL synchronisation phase shift.

The configuration tables may be pre-programmed by the controllerdesigner and hardwired into the controller design. Alternatively, theconfiguration tables may be programmable. The programming of theconfiguration tables may be performed during manufacture or in asubsequent customisation step. For example, the controller may beprovided with a communications port, for example a serial port. Byplacing the controller in a set-up mode, the controller may beconfigured to allow the programming of the configuration tables inmemory using data received from the serial port.

A more detailed implementation of an exemplary controller will now beexplained with reference to FIG. 4. In brief, the controller 14 which issuitably fabricated on a single integrated circuit comprises twoprocessors 50, 52 responsible for the operation of the controller. Thefirst processor 50 is responsible for the direct control of the desiredvoltage\current being delivered by the converter to a load. The firstprocessor may be purposely designed for this task and is generallyselected to be able to respond quickly to changing loads etc. The firstprocessor acts upon external measurements received, including forexample sensed output voltage, current and temperature. The firstprocessor using control algorithms and parameter settings (as previouslydescribed) including for example voltage set point provides one or morecontrol signals to a digital pulse width modulator 54. The digital pulsewidth modulator in turn generates a plurality of switching signals 56 todrive the converter. These switching signals are provided through pinsof the integrated circuit to power switches in a power stage beingcontrolled by the controller. The power stage may be configured in anyof several different topologies including for example, buck and boost.The power stage in turn through the switching of the power switchesconverts an input supply voltage to another voltage and provides this toa local load. The input voltage may be greater than or less than thevoltage supplied to the load and may have the same or different polaritydepending on the arrangement of the power stage and the configurationsettings of the controller.

The second processor 52 provided within the controller is forhousekeeping purposes. The use of the second processor ensures that theprimary processor is not distracted from its primary purpose ofcontrolling the power stage through the DPWM. The second processor mayfor example facilitate communications, for example through acommunications circuit 58 over a serial communications bus, withexternal devices. It will be appreciated that a controller may beprovided with just a single processor combining the functions of bothprocessors or indeed their roles may be further broken down with morethan two processors present.

One or more analog inputs (V_(sense), I_(sense), Temp, and R_(config))are provided to the controller at designated pins. These analog inputsmay include signals being measured including for example Vout, lout andtemperature. The analog inputs also include one or more configurationpins 62.

Each of the analog input pins may have an associated signal conditioningcircuit (60 a-d). Thus where the pin is “programmed” by a resistor, aknown current may be generated by the associated signal conditioningcircuit (60 d) in the controller and injected at the pin 62. Other pinsmay have signal conditioning circuits that include scaling andfiltering. Each analog input may be connected via a multiplexor 64 to ananalog to digital converter 66. The multiplexor is configured to switchthe input to the ADC in response to instructions from one or either orboth of the processors. Thus for example, the second processor mayemploy the multiplexor and ADC to obtain particular settings onstart-up, e.g. from a measurement of the resistance at a programming pinwith the first processor employing the multiplexor and ADC forin-circuit measurements during normal operation. It will be appreciatedthat the use of the multiplexor obviates the need for multiple ADCcircuits.

Whilst it will be appreciated that the use of a multiplexor with asingle ADC offers a considerable saving in space and power within anintegrated circuit, the resolution of the ADC is determined with respectto the input requiring the greatest possible resolution, thus forcertain inputs including pin programming, the full resolution, forexample 12 bits, of the output from the ADC may not be required.Accordingly, depending on the input signal the digital output from theADC may be truncated (with or without rounding) to a lower resolutiondigital signal. The measurements from the ADC are available to othercomponents within the integrated circuit over a suitable internal bus orother arrangement. Thus a voltage measurement may be provided tomultiple circuits within the integrated circuit. For example, a faultprotection circuit 68 may be included which limits the operation of theDPWM in response to a detected fault condition, e.g. an over-voltage.

During start-up, periodically or in response to an external trigger, ameasurement is made at a programming pin of a programming resistor toobtain a programming value. This voltage measurement is provided fromthe ADC to the second processor 52 which is responsible for thehousekeeping functions of the controller. This second processor in turndetermines an appropriate configuration from the measurement for exampleby using the determined resistor value as input to a configurationpointer table 80, as shown in FIG. 5, to determine a pointer from themeasurement. The determined pointer may then be used to retrieve aconfiguration table 82 a-c from memory 70. The configuration settingsmay then be provided to and employed by the first processor 50 or indeedother circuits (e.g. DPWM 54 or fault protection 68) within thecontroller to operate the controller in a desired manner. In contrast tothe prior art, the present application allows for the configuration ofmultiple parameters using one component connected to a singleprogramming pin.

To determine the appropriate configuration, the second processor directsthe multiplexor to connect the appropriate configuration pin to the ADC.A measurement of the voltage (and hence resistance of the programmingresistor) at the pin is then provided by the ADC to the secondprocessor.

The second processor in turn determines a configuration pointer from theresistance measurement. This determination may be made with reference toa reference table or algorithm. Thus for example as previously describeda resistor bin value may be employed as input to a pointer referencetable from which a pointer is obtained in response.

Where more than two programming pins are employed together, the secondprocessor may use the two resistor bin values together as inputs to thepointer reference table to determine an appropriate pointer. The pointerreference table may be inherent as explained before or it may be storedin memory. An advantage of storing the reference table in memory is thatit may be programmed by a user. Thus where there are only, for example 5configuration tables provided but 12 different possible resistor bins,then the pointers for the non-required resistor bins may be programmedto be a default pointer which in turn points to a default configurationtable.

The determined pointer value is then used by the second processor toretrieve a corresponding configuration table from memory. For eachdistinct pointer value 84 a-c, there is a corresponding configurationtable 82 a-c. Each configuration table stores values for a plurality ofdifferent parameters. The values stored in each configuration table arepre-programmed into the controller during a manufacturing or subsequentcustomisation stage. It will be appreciated that the number of differentcombinations is limited by the number of different configuration tablesstored which in turn is limited by the maximum pointer value available.However in reality, only a limited number of different configurationtables may be required. In such a scenario, unused pointers in thepointer table may be directed to point to a default configuration table.

A converter may be shipped with an arbitrary number of configurationtables stored in the device. Configuration tables may be stored insuitable types of memory (e.g. ROM, or NVM). If programmable,configuration tables may be programmed into the device by either thecontroller manufacturer, an out-source partner specialising in ICprogramming, or the power circuit manufacturer at a pre-assemblymanufacturing stage.

The configuration settings in a configuration table may either bedefined by the controller manufacturer, or specified by a circuitdesigner using the controller in order to serve a particular need in acircuit. A user of a controller may order from the controllermanufacturer a controller part with a plurality of, for example 100,different configuration tables, allowing the user to use the controllerin a correspondingly large number of different power conversionapplications, while retaining the freedom to select one configurationtable for a particular application using one or more configurationinputs in combination with associated configuration resistors. Theadvantage of this approach is that the controller user need to hold onlyone variety of controller in stock (simplified material management,reduced cost) while selection of one particular configuration table isstraight-forward by means of a resistor which is both robust andflexible. In contrast to prior art, a much reduced number of externalcomponents is required, plus an arbitrary number of configurationsettings may be achieved as configuration tables may contain a largenumber of configuration settings. Thus for a device with 50 differentparameter settings, the circuit designer may elect 10 differentconfigurations to suit ten different converter circuits. The samecontroller may be used in each of the ten different converter circuitsand the 50 different parameters will be set in each converter circuit bya single programming resistor.

Whilst the above explanation has been made with respect to configurationtables 82 a-c being programmable, the configuration pointer table mayalso be configured to be programmable as shown in the arrangement ofFIG. 6. In this arrangement, a controller may be manufactured andshipped with an arbitrary number of configuration tables 82 a-c. Thecontroller user can however customise the mapping to the configurationtable by altering pointers values 86 a-d within the pointer table 80.Thus a reduced number of configuration tables may be made available. Insuch an arrangement, the pointer reference table may be updated to setunwanted pointer values to a default value.

Whilst the above description has been made with reference to the use ofreference tables it will be appreciated that other techniques arepossible. Thus for example, the software code itself implemented by oneor more processors may be altered to set different values for multipleparameters in response to differently determined resistance bin values.Although, it will be appreciated that this is a cumbersome approach.Alternatively, a combination of the two techniques may be employed. Forexample, a determination of one parameter may be made with respect towhether the attached programming resistor is greater than or less than aparticular value with a further determination one or more otherparameters made based on which resistance bin the programming resistorfalls into as previously described.

Whilst the technique of the present application may be used with morethan one programming pin, it will be appreciated that the number ofdifferent parameters which may be set are limited not by the number ofpins but by the contents of the configuration tables. Generally howeverthe number of parameters being set by programming resistors using thepresent method will be greater than the number of programming resistorsused for this purpose.

It will be appreciated that the present technique may be combined withthose from the prior art and thus one programming pin or set of pins maybe employed using the techniques described above for setting a first setof parameter values with another programming pin or set of pins usingthe techniques of the prior art for setting one or more other parametervalues.

For the purposes of explanation, the following is a list ofabbreviations employed in the current specification.

Abbreviations

ADC Analogue-digital converter BOM Bill of material IC IntegratedCircuit MTBF Mean time between failures (relating to random failurerates of electronic systems) NVM Non-volatile memory OCP Over-currentprotection (relating to output current lout) OTP Over-temperatureprotection OVP Over-voltage protection (relating to output voltage Vout)POL Point of Load. A point of load converter is a non-isolated powerconverter, delivering regulated power to a load in close physicalproximity. POLC POL Controller RAM Random-access memory ROM Read-onlymemory UVLO Under-voltage lockout (relating to input voltage Vin)

It will be appreciated that whilst several different embodiments havebeen described herein, that the features of each may be advantageouslycombined together in a variety of forms to achieve advantage. Thus forexample, whilst the above description has been made with reference to anexemplary controller as employed by the present assignee, it will beappreciated that the method may also be applied and\or incorporatedwithin other adaptive control schemes. Similarly, whilst the abovesystem and method has been described generally with respect to a switchmode power supply, it will be appreciated that the technique may also beapplied to non-switching (linear) power supplies. It will be appreciatedthat in such an arrangement, the DPWM would be replaced with a lineardriving stage and the power stage would be a linear mode power stage.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims. For example, theconnections may be any type of connection suitable to transfer signalsfrom or to the respective nodes, units or devices, for example viaintermediate devices. Accordingly, unless implied or stated otherwisethe connections may for example be direct connections or indirectconnections.

The conductors as discussed herein may be illustrated or described inreference to being a single conductor, a plurality of conductors,unidirectional conductors, or bidirectional conductors. However,different embodiments may vary the implementation of the conductors. Forexample, separate unidirectional conductors may be used rather thanbidirectional conductors and vice versa. Also, plurality of conductorsmay be replaced with a single conductor that transfers multiple signalsserially or in a time multiplexed manner. Likewise, single conductorscarrying multiple signals may be separated out into various differentconductors carrying subsets of these signals. Therefore, many optionsexist for transferring signals.

Because the apparatus implementing the present invention is, for themost part, composed of electronic components and circuits known to thoseskilled in the art, circuit details will not be explained in any greaterextent than that considered necessary as illustrated above, for theunderstanding and appreciation of the underlying concepts of the presentinvention and in order not to obfuscate or distract from the teachingsof the present invention.

Thus, it is to be understood that the architectures depicted herein aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In an abstract, butstill definite sense, any arrangement of components to achieve the samefunctionality is effectively “associated” such that the desiredfunctionality is achieved. Hence, any two components herein combined toachieve a particular functionality can be seen as “associated with” eachother such that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the functionality of the above described operations merelyillustrative. The functionality of multiple operations may be combinedinto a single operation, and/or the functionality of a single operationmay be distributed in additional operations. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

Also, the invention is not limited to physical devices or unitsimplemented in non-programmable hardware but can also be applied inprogrammable devices or units able to perform the desired devicefunctions by operating in accordance with suitable program code.Furthermore, the devices may be physically distributed over a number ofapparatuses, while functionally operating as a single device.

However, other modifications, variations and alternatives are alsopossible. The specifications and drawings are, accordingly, to beregarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps than those listed in aclaim. Furthermore, the terms “a” or “an,” as used herein, are definedas one or more than one. Also, the use of introductory phrases such as“at least one” and “one or more” in the claims should not be construedto imply that the introduction of another claim element by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases “oneor more” or “at least one” and indefinite articles such as “a” or “an.”The same holds true for the use of definite articles. Unless statedotherwise, terms such as “first” and “second” are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage. It will beappreciated that the claims of the present application have been writtenin single dependency form to meet the requirements of certainjurisdictions. Accordingly the claims should be taken as being multiplydependent unless the context excludes it and that all combinationsresulting there from should be taken as being provided for.

The invention claimed is:
 1. A method of configuring a controller for aswitching power supply, the controller being configured to provideswitching signals to operate one or more switches at a switchingfrequency, the controller having a plurality of settings determiningoperating parameters for the switching of the one or more switches inthe switching circuit and the controller being provided in an integratedcircuit having a plurality of pins of which only one is a configurationpin configured for pin programming by presenting an impedance to thepin, the method comprising the steps of: a) performing a measurement ofthe impedance presented at the configuration pin, b) using saidmeasurement of the impedance on its own to retrieve three or more storedsettings, and c) configuring the controller with the retrieved three ormore stored settings to control the operation of the one or moreswitches at the switching frequency.
 2. A method according to claim 1,wherein the step of using said measurement comprises: deriving a pointerfrom the measurement; and using the pointer to retrieve a referencetable containing at least one setting.
 3. A method according to claim 2,further comprising a step of programming at least one setting in thereference table.
 4. A method according to claim 3, wherein theprogramming step is performed during the manufacture of the integratedcircuit.
 5. A method according to claim 2, wherein the reference tableis stored in a programmable memory.
 6. A method according to claim 5,wherein the reference table is programmable through a communicationsport on the controller.
 7. A method according to claim 6, wherein thecommunications port is a serial port.
 8. A method according to claim 1,wherein the configuring is performed during a start-up routine of thecontroller.
 9. A configurable controller for a switching powerconverter, the controller being provided in an integrated circuit andcomprising: only one programming pin to which at least one externalprogramming component is connectable; a measurement circuit forperforming a single measurement at the programming pin of the at the atleast one external programming component; wherein the controller isadapted to employ said single measurement on its own as a reference toretrieve three or more stored settings for the controller and toconfigure the controller with the retrieved three or more storedsettings.
 10. A controller according to claim 9, wherein the controlleris configured to employ the measurement to derive a pointer value andadapted to use the pointer value as the reference to retrieve the two ormore stored settings.
 11. A controller according to claim 10, furthercomprising a memory for storing a plurality of configuration tables,with each configuration table storing a plurality of different parametersettings.
 12. A controller according to claim 10, wherein themeasurement circuit comprises an analog to digital converter.
 13. Acontroller according to claim 10, wherein the pointer is obtained from apointer reference table using the measurement or a derivation of themeasurement as an input.
 14. A controller according to claim 13, whereinthe pointer reference table is stored in memory.
 15. A controlleraccording to claim 10, further comprising a memory for storing thestored settings wherein the memory is programmable.
 16. A controlleraccording to claim 15, wherein the memory is programmable duringmanufacture of the integrated circuit.
 17. A controller according toclaim 15, wherein the controller is configured to provide forprogramming of the memory through a communications port on thecontroller.
 18. A controller according to claim 9, wherein at least oneof the settings is the set point for output voltage.
 19. A method ofmanufacturing a configurable controller for a power supply, the methodcomprising the steps of: a) designing the controller as an integratedcircuit with a pin programming feature provided on only one pin of theintegrated circuit; b) fabricating the controller with a memory as anintegrated circuit package with pins of which one is the pin of the pinprogramming feature; and b) storing a plurality of differentconfigurations within the memory, where each individual configurationprovides individual settings for a plurality of different operatingparameters of the configurable controller, and where the pin programmingfeature determines the choice of configuration to be used by thecontroller such that more than three parameters are set solely by thevalue of resistance presented at the pin of the pin programming featureof the integrated circuit.
 20. A method of pin programming a controllerfor a power supply, the method comprising the steps of: a) taking asingle measurement at a pin of the controller; b) using said singlemeasurement on its own to select a stored set of settings from aplurality of stored sets of settings, wherein each stored set ofsettings comprises more than three operating parameters of thecontroller; c) setting operating parameters of the controller inaccordance with the retrieved set of settings.
 21. A method according toclaim 1, wherein at least one of the three or more stored settings areone or more of: a) an output voltage set-point; b) a communicationaddress; c) a switching frequency; d) an output current limit; e) aninput Under-Voltage Lockout; f) a maximum output voltage set-point whichcan be commanded; g) an output voltage set-point for margin high test;h) an output voltage set-point for margin low test; i) an output voltageOver-voltage protection trip-point; j) an output voltage offsetcorrection parameter; k) an output voltage rise time; l) an outputvoltage ramp delay following an ON command; m) an output voltage rampdelay following an ON command; n) a programmable response to UnderVoltage Lock Out condition; o) an input voltage over-voltage protectionthreshold; p) a programmable response to Over Voltage Lock Outcondition; q) a programmable response to Over Current Protectioncondition; r) an output current lethal protection; s) a phase dropfeature on/off; t) an output current phase drop threshold; u) anover-temperature protection threshold; v) a programmable response toOver Temperature Protection condition; w) a programmable response toOPERATION command; x) a programmable response to CTRL pin; y) aprogrammable polarity of CTRL pin; z) a minimum duty cycle; aa) amaximum duty cycle; bb) a MOSFET driver type; cc) a multi-Point Of Loadstress share feature; dd) a multi-Point Of Load synchronisation feature;or ee) a multi-POL synchronisation phase shift.
 22. A configurablecontroller according to claim 9, wherein at least one of the three ormore stored settings are one or more of: a) an output voltage set-point;b) a communication address; c) a switching frequency; d) an outputcurrent limit; e) an input Under-Voltage Lockout; f) a maximum outputvoltage set-point which can be commanded; g) an output voltage set-pointfor margin high test; h) an output voltage set-point for margin lowtest; i) an output voltage Over-voltage protection trip-point; j) anoutput voltage offset correction parameter; k) an output voltage risetime; l) an output voltage ramp delay following an ON command; m) anoutput voltage ramp delay following an ON command; n) a programmableresponse to Under Voltage Lock Out condition; o) a input voltageover-voltage protection threshold; p) a programmable response to OverVoltage Lock Out condition; q) a programmable response to Over CurrentProtection condition; r) an output current lethal protection; s) a phasedrop feature on/off; t) an output current phase drop threshold; u) anover-temperature protection threshold; v) a programmable response toOver Temperature Protection condition; w) a programmable response toOPERATION command; x) a programmable response to CTRL pin; y) aprogrammable polarity of CTRL pin; z) a minimum duty cycle; aa) amaximum duty cycle; bb) a MOSFET driver type; cc) a multi-Point Of Loadstress share feature; dd) a multi-Point Of Load synchronisation feature;or ee) a multi-POL synchronisation phase shift.
 23. A method accordingto claim 19, wherein at least one of the three parameters are one ormore of: a) output voltage set-point; b) a communication address; c)Switching frequency; d) an output current limit; e) an inputUnder-Voltage Lockout; f) a maximum output voltage set-point which canbe commanded; g) an output voltage set-point for margin high test; h) anoutput voltage set-point for margin low test; i) an output voltageOver-voltage protection trip-point; j) an output voltage offsetcorrection parameter; k) an output voltage rise time; l) an outputvoltage ramp delay following an ON command; m) an output voltage rampdelay following an ON command; n) a programmable response to UnderVoltage Lock Out condition; o) an input voltage over-voltage protectionthreshold; p) a programmable response to Over Voltage Lock Outcondition; q) a programmable response to Over Current Protectioncondition; r) an output current lethal protection; s) a phase dropfeature on/off; t) an output current phase drop threshold; u) anover-temperature protection threshold; v) a programmable response toOver Temperature Protection condition; w) a programmable response toOPERATION command; x) a programmable response to CTRL pin; y) aprogrammable polarity of CTRL pin; z) a minimum duty cycle; aa) amaximum duty cycle; bb) a MOSFET driver type; cc) a multi-Point Of Loadstress share feature; dd) a multi-Point Of Load synchronisation feature;or ee) a multi-POL synchronisation phase shift.
 24. A method accordingto claim 20, wherein at least one of the three operating parameters areone or more of: a) an output voltage set-point; b) a communicationaddress; c) a witching frequency; d) an output current limit; e) aninput Under-Voltage Lockout; f) a maximum output voltage set-point whichcan be commanded; g) an output voltage set-point for margin high test;h) an output voltage set-point for margin low test; i) an output voltageOver-voltage protection trip-point; j) an output voltage offsetcorrection parameter; k) an output voltage rise time; l) an outputvoltage ramp delay following an ON command; m) an output voltage rampdelay following an ON command; n) a programmable response to UnderVoltage Lock Out condition; o) an input voltage over-voltage protectionthreshold; p) a programmable response to Over Voltage Lock Outcondition; q) a programmable response to Over Current Protectioncondition; r) an output current lethal protection; s) a phase dropfeature on/off; t) an output current phase drop threshold; u) anover-temperature protection threshold; v) a programmable response toOver Temperature Protection condition; w) a programmable response toOPERATION command; x) a programmable response to CTRL pin; y) aprogrammable polarity of CTRL pin; z) a minimum duty cycle; aa) amaximum duty cycle; bb) a MOSFET driver type; cc) a multi-Point Of Loadstress share feature; dd) a multi-Point Of Load synchronisation feature;or ee) a multi-POL synchronisation phase shift.